Power battery and battery module

ABSTRACT

The disclosure relates to a power battery and a battery module. The power battery includes: a case including two openings opposite to each other; an electrode assembly formed by winding a positive electrode sheet, a negative electrode sheet, and a separator disposed around a winding axis, the electrode assembly being disposed in the case, and two opposite ends of the electrode assembly along the winding axis being respectively disposed corresponding to the two openings; a first cap assembly covering one of the two openings, the first cap assembly including a liquid injection hole communicating with an interior of the case; a second cap assembly covering the other opening, the second cap assembly including a through hole communicating with the interior of the case; in a length direction, the liquid injection hole and the through hole are located on a same side of a central axis of the case.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No.PCT/CN2018/083386, filed on Apr. 17, 2018, which claims priority toChinese Patent Application No. 201820179736.3, filed on Feb. 1, 2018,both of which are incorporated herein by reference in their entireties.

TECHNICAL FIELD

The disclosure relates to the technical field of power battery, and inparticular to a power battery and a battery module.

BACKGROUND

The power battery generally includes an electrode assembly, a case, anda cap assembly. The electrode assembly is formed by winding a positiveelectrode sheet, a negative electrode sheet, and a separator disposedbetween the positive electrode sheet and the negative electrode sheetaround a winding axis. The electrode assembly is accommodated in thecase, and the cap assembly is assembled together with the case and isdisposed corresponding to an end of the electrode assembly along thewinding axis. The cap assembly includes a cap plate and an electrodeterminal disposed in the cap plate, and herein a tab of the electrodeassembly is electrically connected to the electrode terminal of the capassembly. The cap plate includes a liquid injection hole communicatingwith a closed space.

SUMMARY

Embodiments of the disclosure provide a power battery and a batterymodule. The power battery protects the end of the electrode assemblyduring the liquid injection, and reduces a probability that a shortcircuit occurs between a positive electrode sheet and a negativeelectrode sheet.

one aspect, embodiments of the disclosure provide a power battery,including: a case including two openings opposite to each other; anelectrode assembly which is formed by winding a positive electrodesheet, a negative electrode sheet, and a separator disposed between thepositive electrode sheet and the negative electrode sheet around awinding axis, the electrode assembly being disposed in the case, and twoopposite ends of the electrode assembly along the winding axis beingrespectively disposed corresponding to the two openings; a first capassembly covering one of the two openings, the first cap assemblyincluding an liquid injection hole communicating with an interior of thecase; a second cap assembly covering the other of the two openings, thesecond cap assembly including a through hole communicating with theinterior of the case; in a length direction, the liquid injection holeand the through hole are located on a same side of a central axis of thecase.

another aspect, embodiments of the disclosure provide a battery moduleincluding a plurality of power batteries as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of theembodiments of the disclosure, the drawings used in the embodiments ofthe disclosure will be briefly described below; it is obvious that thedrawings described below are only some embodiments of the disclosure;and for those skilled in the art, other drawings can be obtainedaccording to the drawings without any creative work.

FIG. 1 is an exploded structural view of a power battery according to anembodiment of the disclosure;

FIG. 2 is a structural sectional view of a power battery according to afirst embodiment of the disclosure;

FIG. 3 is a structural sectional view of a power battery according to asecond embodiment of the disclosure;

FIG. 4 is a structural sectional view of a power battery according to athird embodiment of the disclosure.

The views are not necessarily plotted in actual proportion in thedrawings.

REFERENCE SIGNS IN THE DRAWINGS

-   -   1 case;    -   1 a central axis of case;    -   2 electrode assembly;    -   21 tab;    -   3 first cap assembly;    -   31 liquid injection hole;    -   31 a first inlet;    -   31 b first outlet;    -   32 first cap plate;    -   33 first vent film;    -   33 a axis;    -   34 first electrode terminal;    -   35 first blocking member;    -   36 first guide channel;    -   4 second electrode terminal;    -   41 through hole;    -   41 a second inlet;    -   41 b second outlet;    -   42 second cap plate;    -   43 second vent film;    -   43 a axis;    -   44 second electrode terminal;    -   45 second blocking member;    -   46 second guide channel;    -   X length direction;    -   Y height direction.

DETAILED DESCRIPTION

Below, embodiments of the disclosure will be further described in detailwith reference to the drawings and embodiments. The detailed descriptionaccording to the embodiments and the accompanying drawings below areintended to exemplary illustrate the principles of the disclosure andare not intended to limit the scope of the disclosure, i.e., thedisclosure is not limited to the described embodiments and the scope ofthe disclosed is defined by the claims.

In the description of the disclosure, it should be noted that, unlessotherwise stated, the meaning of “a plurality” is two or more; theorientation or positional relationship indicated by the terms “upper”,“lower”, “left”, “right”, “inner”, “outer” and the like is merely forthe purpose of describing the disclosure and simplifying thedescription, and is not intended to indicate or imply that the device orcomponent referred to has a particular orientation, is constructed andoperated in a particular orientation, and therefore cannot be understoodto be a limitation of the disclosure. Moreover, the terms “first”,“second”, and the like are configured for descriptive purposes only andare not to be construed as indicating or implying relative importance.

In the description of the disclosure, it should be noted that, unlessotherwise stated, the terms “installation”, “connected to”, and“connected with” are to be understood broadly, and may be, for example,a fixed connection, a disassemble connection, or an integral connection;they can be connected directly or indirectly through an intermediatemedium. The specific meaning of the above terms in the disclosure can beunderstood by the person skilled in the art according to actualcircumstance.

Since a liquid injection hole in a cap plate of a power battery isusually disposed facing an end of an electrode assembly along a windingaxis, when an axis of the liquid injection hole is in a verticaldirection, an electrolyte that is injected into a case through theliquid injection hole will flow in the vertical direction (in order toimprove the efficiency of electrolyte injection, it is often necessaryto increase the injection pressure of the electrolyte), such that theelectrolyte will impact the end of the electrode assembly along thewinding axis. At this time, due to the excessive impact force of theelectrolyte, a separator between a positive electrode sheet and anegative electrode sheet at the end position will be deformed anddisplaced, which will cause the positive electrode sheet and thenegative electrode sheet to contact each other and cause a shortcircuit.

For better understanding of the disclosure, power batteries according toembodiments of the disclosure will be described below in detail withreference to FIGS. 1 to 4.

FIG. 1 schematically shows an exploded structure of a power batteryaccording to an embodiment of the disclosure. FIG. 2 schematically showsa cross-sectional structure of a power battery according to a firstembodiment of the disclosure. FIG. 3 schematically shows across-sectional structure of a power battery according to a secondembodiment of the disclosure. FIG. 4 schematically shows across-sectional structure of a power battery according to a thirdembodiment of the disclosure.

As shown in FIG. 1, the power battery according to the embodiment of thedisclosure includes a case 1, an electrode assembly 2 disposed in thecase 1, and a first cap assembly 3 and a second cap assembly 4 bothconnected to the case 1. The case 1 includes two openings. The electrodeassembly 2 is formed by winding a positive electrode sheet, a negativeelectrode sheet, and a separator disposed between the positive electrodesheet and the negative electrode sheet around a winding axis. Theelectrode assembly 2 includes two opposite ends along the winding axis.After the positive electrode sheet, the negative electrode sheet, andthe separator disposed between the positive electrode sheet and thenegative electrode sheet are wound, a spiral winding is formed at eachend. The electrode assembly 2 is disposed in the case 1, and the twoopposite ends of the electrode assembly 2 along the winding axis arerespectively disposed corresponding to the two openings. The first capassembly 3 covers one of the openings, and the second cap assembly 4covers the other opening.

The placement position of the first cap assembly 3 shown in FIG. 1 istaken as an object, an overall height direction of the first capassembly 3 is taken as a height direction Y, an overall length directionof the first cap assembly 3 is taken as a length direction X, and adirection perpendicular to both the height direction Y and the lengthdirection X is taken as a width direction (not marked in the drawings).

The first cap assembly 3 according to the embodiment includes a liquidinjection hole 31 communicating with an interior of the case 1. Thesecond cap assembly 4 includes a through hole 41 communicating with theinterior of the case 1. In the length direction X, the liquid injectionhole 31 of the first cap assembly 3 and the through hole 41 of thesecond cap assembly 4 are located on a same side of a central axis 1 aof the case 1. The central axis 1 a of the case 1 refers to a centralaxis of the case 1 along the height direction Y. Two portions of thecase 1 at two respective sides of the central axis 1 a are substantiallysymmetrical with respect to the central axis 1 a. On one hand, when thepower battery needs to be filled with liquid, the power battery can beplaced horizontally (as shown in FIGS. 2 to 4), i.e., the first capassembly 3 is in a vertical state, and then the liquid injectionoperation is performed. The liquid injection hole 31 disposed in thefirst cap assembly 3 is at a high position, and an electrolyte injectedinto the case 1 through the liquid injection hole 31 will flow along aparabolic trajectory due to its own gravity, which thereby effectivelyreduces a horizontal impact force on the end of the electrode assembly 2and reduces a probability that a short circuit occurs between thepositive electrode sheet and the negative electrode sheet due toinsulation failure which may be caused by the displacement of theseparator under the impact of the electrolyte. In another aspect, sincethe liquid injection hole 31 in the first cap assembly 3 and the throughhole 41 in the second cap assembly 4 are located on the same side of thecentral axis 1 a of the case 1, gas inside the case 1 can be dischargedfrom the power battery through the through hole 41 when the liquid isinjected through the liquid injection hole 31, which facilitates quickliquid injection. On the other hand, since the liquid injection hole 31in the first cap assembly 3 and the through hole 41 in the second capassembly 4 are located on the same side of the central axis 1 a of thecase 1, it is ensured that the electrolyte will not overflow from thethrough hole 41 when the liquid is injected through the liquid injectionhole 31, and it is ensured that enough electrolyte will be injected. Instill another aspect, the electrolyte may be injected into the case 1through both the liquid injection hole 31 and the through hole 41 at thesame time, which improves the efficiency of liquid injection. When it isnecessary to inject the liquid through the through hole 41, the throughhole 41 disposed in the second cap assembly 4 is also at a highposition, and the electrolyte discharged from the through hole 41 willflow along a parabolic trajectory due to its own gravity, which therebyeffectively reduces a horizontal impact force on the end of theelectrode assembly 2 and reduces a probability that a short circuitoccurs between the positive electrode sheet and the negative electrodesheet due to insulation failure which may be caused by the displacementof the separator under the impact of the electrolyte.

According to the embodiment, a projection of the liquid injection hole31 in the height direction Y at least partially overlaps with aprojection of the through hole 41 in the height direction Y. When theliquid injection operation of the power battery is performed, the liquidinjection hole 31 and the through hole 41 may be approximately in thesame horizontal position with each other, which helps to increase theliquid injection amount of the power battery.

In one embodiment, an axis of the liquid injection hole 31 coincideswith an axis of the through hole 41, which can further increase theliquid injection amount of the power battery. Optionally, a shape of theliquid injection hole 31 is the same as a shape of the through hole 41,which reduces the difficulty of manufacturing.

The liquid injection hole 31 according to the embodiment is disposed atan end of the first cap assembly 3 along the length direction X. Thethrough hole 41 is disposed at an end of the second cap assembly 4 alongthe length direction X. In this way, more electrolyte can be furtherinjected into the case 1.

For the power battery according to embodiments of the disclosure, whenthe power battery is filled with liquid, since an electrolyte injectedinto the case will flow along a parabolic trajectory due to its owngravity and does not vertically impact the end of the electrodeassembly, the impact force on the end of the electrode assembly will bereduced, which thereby reduces a probability that a short circuit occursbetween the positive electrode sheet and the negative electrode sheetwhich may be caused by the displacement of the separator included in theelectrode assembly under the impact of the electrolyte, improves a yieldof the power battery after the liquid injection operation is finished,and also eliminates hidden dangers of the power battery and ensures thesafety in the subsequent use.

The technical solution will be further described clearly below withreference to specific embodiments, but the following embodiments do notlimit the protection scope of the disclosure.

First Embodiment

As shown in FIG. 2, the first cap assembly 3 according to the embodimentincludes a first cap plate 32 and a first electrode terminal 34 disposedin the first cap plate 32. Taps 21 are disposed at two opposite ends ofthe electrode assembly 2 respectively. The first cap plate 32 isconnected to the case 1. The first electrode terminal 34 is electricallyconnected to one tab 21 on the electrode assembly 2. The liquidinjection hole 31 is disposed in the first cap plate 32. The first capplate 32 includes a top and a bottom opposite to each other in theheight direction Y (the top and the bottom are based on the placementposition as shown in FIG. 1). The liquid injection hole 31 includes afirst inlet 31 a disposed at the top of the first cap plate 32 and afirst outlet 31 b disposed at the bottom of the first cap plate 32. Thesecond cap assembly 4 according to the embodiment includes a second capplate 42 and a second electrode terminal 44 disposed on the second capplate 42. The second cap plate 42 is connected to the case 1. The secondelectrode terminal 44 is electrically connected to the other tab 21 onthe electrode assembly 2. The through hole 41 is disposed in the secondcap plate 42. The second cap plate 42 includes a top and a bottomopposite to each other in the height direction Y (the top and the bottomare based on the placement position as shown in FIG. 1). The throughhole 41 includes a second inlet 41 a disposed at the top of the secondcap plate 42 and a second outlet 41 b disposed at the bottom of thesecond cap plate 42.

FIG. 2 schematically shows that the power battery is in a to-be-injectedstate. In one example, the electrolyte is injected from the first inlet31 a of the liquid injection hole 31 and enters the case 1 from thefirst outlet 31 b. The electrolyte discharged from the first outlet 31 bwill flow along a parabolic trajectory due to its own gravity, whichthereby effectively reduces a horizontal impact force on the end of theelectrode assembly 2. When the electrolyte is injected into the case 1through the liquid injection hole 31, the through hole 41 can serve asan exhaust passage, and gas in the case 1 can be discharged through thethrough hole 41. In another example, the electrolyte may be injectedfrom both the first inlet 31 a of the liquid injection hole 31 and thesecond inlet 41 a of the through hole 41 at the same time, whichimproves the efficiency of liquid injection.

In some embodiments, the liquid injection hole 31 is disposed at an endof the first cap plate 32 along the length direction X. The through hole41 is disposed at an end of the second cap plate 42 along the lengthdirection X. A projection of the liquid injection hole 31 in the heightdirection Y completely overlaps with a projection of the through hole 41in the height direction Y. In this way, the injection amount of theelectrolyte can be further increased.

The first cap assembly 3 according to the embodiment includes a firstvent film 33. The first vent film 33 is disposed on the top of the firstcap plate 32. After the liquid injection operation is finished, an edgeof the first vent film 33 and the top of the first cap plate 32 form anannular joint, such that the first vent film 33 and the first cap plate32 are hermetically connected. The first vent film 33 covers the firstinlet 31 a of the liquid injection hole 31. After the electrolyteinjection operation through the liquid injection hole 31 is finished,the first vent film 33 is hermetically connected to the top of the firstcap plate 32, and the through hole 41 is also blocked to ensure that theinterior of the power battery is in a sealed state. When the pressureinside the power battery is greater than a design pressure of the firstvent film 33, the first vent film 33 will be broken, which therebyreleases the internal pressure of the power battery and ensures thesafety of the power battery.

Optionally, the first vent film 33 according to the embodiment may havea strip-shaped structure or a circle-shaped structure.

An axis of the first inlet 31 a of the liquid injection hole 31according to the embodiment is arranged offset from an axis 33 a of thefirst vent film 33, and the axis 33 a of the first vent film 33 iscloser than the axis of the first inlet 31 a to the central axis 1 a ofthe case 1. The axis 33 a of the first vent film 33 refers to a centralaxis of the first vent film 33 along the height direction Y, and thefirst vent film 33 is substantially symmetrical with respect to the axis33 a. In this way, on one hand, it is beneficial to increase aforce-bearing area of the first vent film 33; and on the other hand, adiameter of the liquid injection hole 31 can be made small, thus whenthe liquid is injected from the liquid injection hole 31, moreelectrolyte can be injected into the case 1 and it can be effectivelyprevented that the electrolyte overflows from the liquid injection hole31. A surface area of the first vent film 33 located within the annularjoint is the effective force-bearing area of the first vent film 33. Thegas discharged from the liquid injection hole 31 can apply a compressiveforce on the surface of the first vent film 33 located within theannular joint. A cross-sectional area of the liquid injection hole 31refers to a projected area of the liquid injection hole 31 along theheight direction Y. The larger the surface area of the first vent film33 located within the annular joint, the lower the pressure required forits breaking. According to product requirements, the first vent film 33is selected to have a suitable size to effectively ensure the safety ofthe power battery.

The top of the first cap plate 32 according to the embodiment includes aconcave portion that is recessed toward the bottom. The liquid injectionhole 31 is in communication with the recess, and the first vent film 33is accommodated in the recess. The concave portion disposed at the topof the first cap plate 32 can position the first vent film 33 so as toquickly install and fix the first vent film 33 at a predeterminedposition on the first cap plate 32. Also, it is convenient to weld thejoint formed between the first vent film 33 and the first cap plate 32,and it is beneficial to realize a quick connection between the firstvent film 33 and the first cap plate 32. Furthermore, it can be avoidedthat the first vent film 33 disposed increases a thickness of the firstcap plate 32.

The second cap assembly 4 according to the embodiment includes a secondvent film 43. The second vent film 43 is disposed on the top of thesecond cap plate 42. After the liquid injection operation is finished,an edge of the second vent film 43 and the top of the second cap plate42 form an annular joint, such that the second vent film 43 and thesecond cap plate 42 are hermetically connected. The second vent film 43covers the second inlet 41 a of the through hole 41. After theelectrolyte injection operation is finished, the second vent film 43 ishermetically connected to the top of the second cap plate 42 to seal thethrough hole 41 so as to ensure that the interior of the power batteryis in a sealed state. When the pressure inside the power battery isgreater than a design pressure of the second vent film 43, the secondvent film 43 will be broken, which thereby releases the internalpressure of the power battery and ensures the safety of the powerbattery.

Optionally, the second vent film 43 according to the embodiment may havea strip shape or a circular shape.

Optionally, an axis of the second inlet 41 a of the through hole 41according to the embodiment is arranged offset from an axis 43 a of thesecond vent film 43, and the axis 43 a of the second vent film 43 iscloser than the axis of the second inlet 41 a to the central axis 1 a ofthe case 1. The axis 43 a of the second vent film 43 refers to a centralaxis of the second vent film 43 along the height direction Y, and thesecond vent film 43 is substantially symmetrical with respect to theaxis 33 a. In this way, on one hand, it is beneficial to increase aforce-bearing area of the second vent film 43; and on the other hand,when the liquid is injected from the through hole 41, more electrolytecan be injected into the case 1 and it can be effectively prevented thatthe electrolyte reversely overflows from the through hole 41.

A surface area of the second vent film 43 located within the annularjoint is the effective force-bearing area of the second vent film 43.The gas discharged from the through hole 41 can apply a compressiveforce on the surface of the second vent film 43 located within theannular joint. A cross-sectional area of the through hole 41 refers to aprojected area of the through hole 41 along the height direction Y. Thelarger the surface area of the second vent film 43 located within theannular joint, the lower the pressure required for its breaking.According to product requirements, the second vent film 43 is selectedto have a suitable size to effectively ensure the safety of the powerbattery.

The top of the second cap plate 42 according to the embodiment includesa concave portion that is recessed toward the bottom. The through hole41 is in communication with the recess, and the second vent film 43 isaccommodated in the recess. The concave portion disposed at the top ofthe second cap plate 42 can position the second vent film 43 so as toquickly install and fix the second vent film 43 at a predeterminedposition on the second cap plate 42. Also, it is convenient to weld thejoint formed between the second vent film 43 and the second cap plate42, and it is beneficial to realize a quick connection between thesecond vent film 43 and the second cap plate 42. Furthermore, it can beavoided that the second vent film 43 disposed increases a thickness ofthe second cap plate 42.

Second Embodiment

In the first embodiment, a case where the liquid injection hole 31 isdisposed in the first cap assembly 3 and the through hole 41 is disposedis the second cap assembly 4 has been described. In this embodiment,description mainly focuses on differences from the first embodiment, andthe same structure will not be repeated in this embodiment.

FIG. 3 shows that the power battery is in a to-be-injected state. Asshown in FIG. 3, the first cap assembly 3 according to the embodimentincludes a first blocking member 35. The first blocking member 35 isdisposed between the first outlet 31 b of the liquid injection hole 31and the electrode assembly 2, and a projection of the first blockingmember 35 in the height direction Y at least partially blocks the firstoutlet 31 b. In this way, when the liquid injection hole 31 is used forliquid injection of the power battery, since the electrolyte injectedfrom the liquid injection hole 31 is blocked by the first blockingmember 35, a flow rate of the electrolyte injected at a high pressurewill be slowed, and the impact force on the end of the electrodeassembly 2 will be reduced. Thereby, it reduces a probability that ashort circuit occurs between the positive electrode sheet and thenegative electrode sheet which may be caused by the displacement of theseparator included in the electrode assembly 2 under the impact of theelectrolyte, improves a yield of the power battery after the liquidinjection operation is finished, and also eliminates hidden dangers ofthe power battery and ensures the safety in the subsequent use.

In some embodiments, the projection of the first blocking member 35 inthe height direction Y completely blocks the first outlet 31 b of theliquid injection hole 31, such that all the electrolyte discharged fromthe first outlet 31 b of the liquid injection hole 31 has to turn apredetermined angle before entering the case 1, which furthereffectively prevents the electrolyte from impacting the end of theelectrode assembly 2.

Optionally, the liquid injection hole 31 is disposed at the end of thefirst cap plate 32 along the length direction X. A first guide channel36 is formed between the first blocking member 35 and the first capplate 32. The first guide channel 36 communicates with the first outlet31 b of the liquid injection hole 31. An outlet of the first guidechannel 36 is oriented towards the central axis 1 a of the case 1. Thefirst guide channel 36 and the liquid injection hole 31 are at apredetermined angle. The electrolyte injected from the first inlet 31 aof the liquid injection hole 31 flows to the outlet of the liquidinjection hole 31 along the height direction Y, and turns apredetermined angle due to obstruction of the first blocking member 35,and then is discharged through the first guide channel 36, such that theelectrolyte will not continue to flow in the height direction Y when itis discharged from the first outlet 31 b of the liquid injection hole31, and thus the flow rate of the electrolyte injected at high pressurewill be slowed and the resultant impact force on the end of theelectrode assembly 2 will be reduced.

Optionally, the predetermined angle formed between the first guidechannel 36 and the liquid injection hole 31 is 90°, such that theelectrolyte is injected into the liquid injection hole 31 along theheight direction Y and discharged from the first guide channel 36 alongthe length direction X, which reduces the impact force of theelectrolyte on the electrode assembly 2 along the height direction Y.

Optionally, the first blocking member 35 and the first cap plate 32according to the embodiment have an integrated structure, which improvesa connection strength of them, and also facilitates one-timemanufacturing, reducing manufacturing procedures and manufacturingdifficulties.

Optionally, the first blocking member 35 according to the embodiment hasa plate-shaped structure.

Third Embodiment

In the second embodiment, a case where the first blocking member 35 isfurther disposed in the first cap assembly 3 has been described. In thisembodiment, description mainly focuses on differences from the secondembodiment, and the same structure will not be repeated in thisembodiment.

FIG. 4 shows that the power battery is in a to-be-injected state. Asshown in FIG. 4, the second cap assembly 4 according to the embodimentincludes a second blocking member 45. The second blocking member 45 isdisposed between the second outlet 41 b of the through hole 41 and theelectrode assembly 2, and a projection of the second blocking member 45in the height direction Y at least partially blocks the second outlet 41b. In this way, when the through hole 41 is used for liquid injection ofthe power battery, since the electrolyte injected from the through hole41 is blocked by the second blocking member 45, a flow rate of theelectrolyte injected at a high pressure will be slowed, and the impactforce on the end of the electrode assembly 2 will be reduced, whichthereby reduces a probability that a short circuit occurs between thepositive electrode sheet and the negative electrode sheet which may becaused by the displacement of the separator included in the electrodeassembly 2 under the impact of the electrolyte, improves a yield of thepower battery after the liquid injection operation is finished, and alsoeliminates hidden dangers of the power battery and ensures the safety inthe subsequent use.

In some embodiments, the projection of the second blocking member 45 inthe height direction Y completely blocks the second outlet 41 b of thethrough hole 41, such that all the electrolyte discharged from thesecond outlet 41 b of the through hole 41 has to turn a predeterminedangle before entering the case 1, which further effectively prevents theelectrolyte from impacting the end of the electrode assembly 2.

Optionally, the through hole 41 is disposed at the end of the second capplate 42 along the length direction X. A second guide channel 46 isformed between the second blocking member 45 and the second cap plate42. The second guide channel 46 communicates with the second outlet 41 bof the through hole 41. An outlet of the second guide channel 46 isoriented towards the central axis 1 a of the case 1. The second guidechannel 46 and the through hole 41 are at a predetermined angle. Theelectrolyte injected from the second inlet 41 a of the through hole 41flows to the outlet of the through hole 41 along the height direction Y,and turns a predetermined angle due to obstruction of the secondblocking member 45, and then is discharged through the second guidechannel 46, such that the electrolyte will not continue to flow in theheight direction Y when it is discharged from the second outlet 41 b ofthe through hole 41, and thus the flow rate of the electrolyte injectedat high pressure will be slowed and the resultant impact force on theend of the electrode assembly 2 will be reduced.

Optionally, the predetermined angle formed between the second guidechannel 46 and the through hole 41 is 90°, such that the electrolyte isinjected into the through hole 41 along the height direction Y anddischarged from the second guide channel 46 along the length directionX, which reduces the impact force of the electrolyte on the electrodeassembly 2 along the height direction Y.

Optionally, the second blocking member 45 and the second cap plate 42according to the embodiment have an integrated structure, which improvesa connection strength of them, and also facilitates one-timemanufacturing, reducing manufacturing procedures and manufacturingdifficulties.

Optionally, the second blocking member 45 according to the embodimenthas a plate-shaped structure.

For the power battery according to embodiments of the disclosure, whenthe power battery is filled with liquid, since the electrolyte injectedinto the case 1 does not vertically impact the end of the electrodeassembly 2, the impact force on the end of the electrode assembly 2 willbe reduced, which thereby reduces a probability that a short circuitoccurs between the positive electrode sheet and the negative electrodesheet which may be caused by the displacement of the separator includedin the electrode assembly 2 under the impact of the electrolyte,improves a yield of the power battery after the liquid injectionoperation is finished, and also eliminates hidden dangers of the powerbattery and ensures the safety in the subsequent use.

An embodiment of the disclosure also provides a battery module. Thebattery module according to the embodiment includes a plurality of powerbatteries according to the above embodiments. The power batteries arearranged side by side in one direction. Since the power batteryaccording to the embodiment has good safety performance, it can beensured that the battery module as a whole has good safety performance.

Although the disclosure has been described with reference to thepreferred embodiments, various modifications may be made to thedisclosure and components may be replaced with equivalents withoutdeparting from the scope of the disclosure. In particular, the technicalfeatures mentioned in the various embodiments can be combined in anymanner as long as there is no structural conflict. The disclosure is notlimited to the specific embodiments disclosed herein, but includes alltechnical solutions falling within the scope of the claims.

1. A power battery, wherein the power battery comprises: a casecomprising two openings opposite to each other; an electrode assemblywhich is formed by winding a positive electrode sheet, a negativeelectrode sheet, and a separator disposed between the positive electrodesheet and the negative electrode sheet around a winding axis, whereinthe electrode assembly is disposed in the case, and two opposite ends ofthe electrode assembly along the winding axis are respectively disposedcorresponding to the two openings; a first cap assembly covering one ofthe two openings, wherein the first cap assembly comprises a liquidinjection hole communicating with an interior of the case; a second capassembly covering the other of the two openings, wherein the second capassembly comprises a through hole communicating with the interior of thecase; in a length direction, the liquid injection hole and the throughhole are located on a same side of a central axis of the case.
 2. Thepower battery according to claim 1, wherein a projection of the liquidinjection hole in a height direction at least partially overlaps with aprojection of the through hole in the height direction.
 3. The powerbattery according to claim 2, wherein an axis of the liquid injectionhole coincides with an axis of the through hole.
 4. The power batteryaccording to claim 2, wherein the liquid injection hole is disposed atan end of the first cap assembly along the length direction, and thethrough hole is disposed at an end of the second cap assembly along thelength direction.
 5. The power battery according to claim 1, wherein:the liquid injection hole comprises a first inlet and a first outlet,the first cap assembly comprises a first blocking member, the firstblocking member is disposed between the first outlet and the electrodeassembly, and a projection of the first blocking member in the heightdirection at least partially blocks the first outlet.
 6. The powerbattery according to claim 5, wherein: the first cap assembly comprisesa first cap plate, the liquid injection hole and the first blockingmember are disposed at the first cap plate, a first guide channel isformed between the first blocking member and the first cap plate, thefirst guide channel communicates with the first outlet, and an outlet ofthe first guide channel is oriented towards the central axis of thecase.
 7. The power battery according to claim 5, wherein: the throughhole comprises a second inlet and a second outlet, the second capassembly comprises a second blocking member, the second blocking memberis disposed between the second outlet and the electrode assembly, and aprojection of the second blocking member in the height direction atleast partially blocks the second outlet.
 8. The power battery accordingto claim 7, wherein: the second cap assembly comprises a second capplate, the through hole and the second blocking member are disposed atthe second cap plate, a second guide channel is formed between thesecond blocking member and the second cap plate, the second guidechannel communicates with the second outlet, and an outlet of the secondguide channel is oriented towards the central axis of the case.
 9. Thepower battery according to claim 7, wherein: the first cap assemblycomprises a first vent film, the first vent film covers the first inlet,an axis of the first inlet is arranged offset from an axis of the firstvent film, and the axis of the first vent film is closer than the axisof the first inlet to the central axis of the case.
 10. A batterymodule, wherein the battery module comprises a plurality of powerbatteries, and each power battery comprises: a case comprising twoopenings opposite to each other; an electrode assembly which is formedby winding a positive electrode sheet, a negative electrode sheet, and aseparator disposed between the positive electrode sheet and the negativeelectrode sheet around a winding axis, wherein the electrode assembly isdisposed in the case, and two opposite ends of the electrode assemblyalong the winding axis are respectively disposed corresponding to thetwo openings; a first cap assembly covering one of the two openings,wherein the first cap assembly comprises a liquid injection holecommunicating with an interior of the case; a second cap assemblycovering the other of the two openings, wherein the second cap assemblycomprises a through hole communicating with the interior of the case; ina length direction, the liquid injection hole and the through hole arelocated on a same side of a central axis of the case.
 11. The powerbattery according to claim 7, wherein the second cap assembly comprisesa second vent film, the second vent film covers the second inlet, anaxis of the second inlet is arranged offset from an axis of the secondvent film, and the axis of the second vent film is closer than the axisof the second inlet to the central axis of the case.
 12. The powerbattery according to claim 9, wherein the second cap assembly comprisesa second vent film, the second vent film covers the second inlet, anaxis of the second inlet is arranged offset from an axis of the secondvent film, and the axis of the second vent film is closer than the axisof the second inlet to the central axis of the case.
 13. The powerbattery according to claim 9, wherein a top of the first cap platecomprises a concave portion that is recessed toward a bottom of thefirst cap plate, the liquid injection hole is in communication with therecess, and the first vent film is accommodated in the recess.
 14. Thepower battery according to claim 5, wherein the projection of the firstblocking member in the height direction completely blocks the firstoutlet of the liquid injection hole.
 15. The power battery according toclaim 6, wherein a predetermined angle formed between the first guidechannel and the liquid injection hole is 90°.
 16. The power batteryaccording to claim 6, wherein the first blocking member and the firstcap plate have an integrated structure.
 17. The power battery accordingto claim 6, wherein: the through hole comprises a second inlet and asecond outlet, the second cap assembly comprises a second blockingmember, the second blocking member is disposed between the second outletand the electrode assembly, and a projection of the second blockingmember in the height direction at least partially blocks the secondoutlet.
 18. The power battery according to claim 17, wherein: the secondcap assembly comprises a second cap plate, the through hole and thesecond blocking member are disposed at the second cap plate, a secondguide channel is formed between the second blocking member and thesecond cap plate, the second guide channel communicates with the secondoutlet, and an outlet of the second guide channel is oriented towardsthe central axis of the case.
 19. The power battery according to claim18, wherein: the first cap assembly comprises a first vent film, thefirst vent film covers the first inlet, an axis of the first inlet isarranged offset from an axis of the first vent film, and the axis of thefirst vent film is closer than the axis of the first inlet to thecentral axis of the case.
 20. The power battery according to claim 19,wherein the second cap assembly comprises a second vent film, the secondvent film covers the second inlet, an axis of the second inlet isarranged offset from an axis of the second vent film, and the axis ofthe second vent film is closer than the axis of the second inlet to thecentral axis of the case.